Windowed oven door



H. -B. BAUGHMAN ETAL March 28, 1967 WINDOWED OVEN DOOR 2 Sheets-Sheet 1 Filed Dec. 25, 1965 INVENTORS HOWARD B. BAUGHMAN KERMlT B. KEELiNG SR.

4 I x? M THEIR ATTORNEY WINDOWED OVEN DOOR 2 Sheets-Sheet 2 Filed Dec. 23, 1965 INVENTORS HOWARD B.BAUGHMAN &KERM\T a. KEEUNG SR.

THElR ATTORNEY United States Patent OfiFice 3,311 ,106 Patented Mar. 28, 1967 3,311,106 WINDOWED OVEN DOOR Howard B. Baughman and Kermit B. Keeling, Sr., Louisville, lKy., assignors to General Electric Company, a corporation of New York Filed Dec. 23, 1965, Ser. No. 515,910 9 Claims. (Cl. 126-200) The present invention relates to windowed doors and particularly to doors for use with high temperature ovens, such as a self-cleaning baking oven wherein the oven wall temperatures may reach as high as 950 to 1000 F.

This invention was conceived as a much sought after improvement in oven door construction so as to enable a housewife to view the food being cooked in her oven, while retaining for her the advantage of a self-cleaning oven feature that operates on the principle of pyrolysis. The patent to Bohdan Hurko No. 3,121,158, assigned to the General Electric Company, the assignee of this application, describes and claims a basic self-cleaning oven design, and the present invention contemplates the provision of an oven door window for an oven of this kind. Windows have been available in conventional oven doors for many years now. Housewives have become accustomed to the convenience of being able to observe the food while it is being cooked so as to avoid the necessity of opening the oven door and letting out some of the heat in order to judge the degree of doneness of the food. However, windowed oven doors were originally sacrificed as the price one has to pay for gaining the more important feature of an automatic self-cleaning oven. Such self-cleaning ovens operate at a high temperature range above the normal cooking temperature range of 150 F. to 550 F. to somewhere within a range between about 750 and about 950 F. The conventional oven windows were not capable of confining the increased amount of heat energy to the oven cavity and hence they could not be used in a self-cleaning oven door.

The present invention fulfills the need of a windowed oven door for the high temperature self-cleaning oven by providing the window with a movable reflective shield which must be positioned over the window during the high temperature operation, but may be removed during normal cooking operations so that the window is fully useable as in standard ovens with windowed oven doors.

The principal object of the present invention is to provide a door of a domestic oven or other heated cavity with a window that is capable of withstanding high temperatures and should be covered during high temperature oven cleaning operations and which may be uncovered during normal heating operations.

A further object of the present invention is to provide a door for high temperature use with a viewing window for normal temperature operations and a reflective shield which should cover the window during the high temperature operation.

A further object of the present invention is to provide an oven door with a sealed window construction that is provided with a movable reflective shield which is adapted to cooperate with a door latching arrangement whereby the door may not be latched closed unless the reflective shield is covering the window.

A still further object of the present invention is to provide a windowed oven door with a movable shutter within the door structure so as to be able to close the window with the shutter before embarking on a high temperature operation, as well as to provide a shutter interlock device to sense the presence of the shutter in the window closing position, the interlock device being adapted to cooperate with a feeler means on the door frame so that the high temperature operation cannot be initiated unless and until there is the proper relationship between the feeler means and the shutter interlock device.

The present invention in accordance with one form thereof, is embodied in a door construction for a heated cavity where there is a window opening covered by a plurality of glass sheets or lights to form a sealed window. A reflective shield is carried within the door andmovable between a hidden position and a visible position covering the window opening. One portion ofthe door is provided with a door latching means that is adapted to cooperate with a mating element of an oven body for locking the door in a closed position during the high heat clean cycle, as done in the aforementioned Hurko patent. The door also carries a movable interlocking member that normally disables the door latching means. The reflective shield in its visible position serving to deflect the interlocking member away from its disabling position so as to enable the door to be latched when the shield covers the window, and only under this relative position of the shield.

Our invention will be better understood from the following description taken in conjunction with the accompanying drawings and its scope will be pointed out in the appended claims.

FIGURE 1 is a perspective view of a free-standing domestic range having a windowed oven door embodying the present invention;

FIGURE 2 is a cross-sectional, elevational view on an enlarged scale through the center of the door to show the various elements which comprise the door;

FIGURE 3 is a fragmentary elevational view taken on the line 33 of FIGURE 2 and showing the reflective shield in its raised, visible position covering the window as well as deflecting the interlocking member so as to free the door latching means for normal operation;

FIGURE 4 is a fragmentary cross-sectional plan view through the right front corner of the oven on the line 44 of FIGURE 1 with the door shown in its closed position; and

FIGURE 5 is a fragmentary plan view of an oven door latching mechanism used with the windowed oven door of the present invention.

Turning now to a consideration of the drawings, and in particular to FIGURE 1, there is shown for illustrative purposes a free-standing electric range 10 having a top cooking surface 11 with a plurality of surface heating elements 12, a baking oven 13 formed by a box-like oven liner 14 and a front-opening, drop-door 15. Of course, this invention is not limited to use in electric free-standing ranges. The oven could be heated by gas, it could be a built-in oven or any other type of high temperature heated oven cavity. The oven cavity is supplied with two standard heating elements; namely, a lower baking element 16 and an upper broiling element 17 located adjacent the top wall of the oven liner. The back edge of the cooking surface 11 is supplied with a backsplash 18 which supports a control panel including multiple switches 19 for controlling the surface heating elements 12, an oven selector switch 20, and oven thermostat 21 and an oven timer 22 for timing both the cooking operations as well as the oven cleaning cycle. Preferably, the heating elements and their switching controls and timer will be arranged and operated as described in the aforementioned Hurko patent to provide the normal cooking operations and the high temperature oven cleaning operation. Positioned beneath the oven 13 is a pullout drawer 23 which is a storage drawer for cooking utensils and the like. However, in a gas oven this space is usually allotted to a broiler compartment.

As is best seen in FIGURE 2, the oven door 15 is of generally sheet metal construction having three main elements; an outer, decorative door panel 25, an inner door liner 26 and a floating inner panel 27 supported from the inner door liner 26. The outer door panel 25 is of shallow pan-shape by virtue of the fact that it has a slight, rearwardly-turned peripheral flange 29. The inner door liner 26 is also of shallow pan-shape, and it is of mating construction with the outer door panel 25 by virtue of the fact that it has a front-turned peripheral flange 30 which telescopes within the flange 29 of the outer door panel 25. The inner door liner 26 includes a generally rectangular, central, outward embossment 32 of such'a size as to fit closely within the front of the oven frame as is best seen in FIGURE 4.

The floating door panel 27 is likewise of shallow panshape having a front-turned peripheral flange 34, and it covers an area that is slightly less than the area of the outward embossment 32 of the inner door liner. A high temperature gasket 35 is sandwiched between the periphery of the door panel 27 and the inner door liner 26. This floating door panel 27 serves in the manner of a close-fitting plug to close the door opening in the oven liner and to recess the inner face of the oven door back from the front wall of the range cabinet so as to restrict the rise of temperature of the outer walls of the range when the oven is operating at heat cleaning temperatures approaching 1000 F. This floating door panel 27 is fastenedto the inner door liner 26 by means of several fastening means widely spaced around the periphery thereof, only one of which is shown as element 36. A more detailed explanation of this fastening means 36 may be found in a recently issued patent of Clarence Getman, No. 3,189,020 entitled, Oven Door With Floating Inner Panel, which is also assigned to the General Electric Company, the assignee of the present invention.

Attention is directed to FIGURE 4 showing the presence of a low wattage mullion or perimeter heater 37 which encircles the front portion of the oven liner 14 and encompasses the inner door panel 27 therein so as to obtain generally uniform oven wall temperatures throughout the oven. This heater 37'and its function are more fully described in the aforementioned patent to Hurko No. 3,121,158 and it will be controlled along with the other heating elements 16 and 17 as described in that patent.

The oven door 15 is also supplied with a stationary door handle 38 adjacent the top portion thereof. The handle is fastened to the door by screws which extend through the door and have screw heads 39 that are visible on the inner side of the door in FIGURE 1. Moreover, the oven door 15 is hinged to the range body along the bottom edge of the door by means of hinge levers 41 and hinge pins (not shown).

The suitable hinge means for the door is fully described in the patent of George R. Sherman No. 2,873,737 which is assigned to the General Electric Company, the assignee of the present invention.

Looking at FIGURE 2, the present invention relates to a high temperature transparent window 45 formed in the oven door and used by the housewife for viewing the food while it is being cooked in the oven. This window is so constructed that it is protected from the high temperatures experienced in the oven cavity during the selfcleaning operation. The door also has an interlocking means with an oven door latching system so as to preclude the operation of the high temperature cycle unless the oven Window is first protected as will be better understood hereinafter.

A windowopening is formed in each of the three door elements; namely, the outer door panel 25, the inner door liner 26 and the floating inner panel 27. Thus, there is a window opening 47 in the outer door panel 25, window opening 48 in the inner door liner 26 and finally window opening 49in the floating inner panel 27. It is well to provide a plurality of glass panes or sheets in the window openings so as to improve the thermal insulation and retard heat flow. Moreover, it is well to provide for the sealing of the window so as to prevent the escape of odors, vapors as well as convection currents of air. The embodiment best shown in FIGURE 4 of the drawings incorporates three glass sheets 51, 52 and 53. The two frontmost sheets 51 and 52 are first assembled on a continuous spacer frame 54 and they are held together by an outer frame 55 of U-shaped transverse cross-section which slips around the periphery of the glazing unit to form a complete sub-assembly. A decorative trim frame 57 of acute angular shape in transverse crosssection extends around the periphery of the front edge of the outermost glass sheet 51 and it is likewise held in place by the outer frame 55, as is best seen in FIGURE 4. This glazing unit sub-assembly 56 is shown as being fastened to the back side of the outer door panel 25 by means of support flanges 58 and 59 that are in turn screw-fastened by means not shown to a co-operating mounting block 60 and 61, respectively.

The third glass sheet 53 is best shown in FIGURE 2 as being fastened over the window opening 48 in the inner door liner 26 from the inner side thereof by means of fastening screws 36 and clip members 64. In order to seal this glass against the escape of gases and vapors around the edges thereof, a high temperature resilient gasket 65 is sandwiched between the glass 53 and the peripheral edge of the window opening 48. Again, a decorative trim frame 67 is assembled around the peripheral edge of the glass sheet 53 so as to mask the peripheral edge of the glass sheet from View. This trim frame 67 telescopes into the window opening 49 of the floating inner panel 27.

Notice that thermal insulation 70 of fiber glass or the like substantially fills the inner panel 27. An air channel 71 is formed behind the outer door panel 25 by means of an intermediate plate or insulation guard 72 which is closely spaced from the inner surface of the outer panel 25; this channel in area substantially equals the area of the door surrounding the window 45. Suitable air inlet openings 73 are formed along the bottom edge of the door and suitable air outlet openings 74 are formed in the top edge of the door, both communicating with the air channel 71 so that cooling air may pass up through the channel 71. A second insulation guard 69 is located within the inner door liner 26 beneath and along the sides of the window so that insulating material 75 may be confined between the two insulation guards 72 and 69, as is best seen in FIGURE 2.

Attention is directed to a chamber 76 formed between the second insulation guard 69 and the interior surface of the inner door liner 26. The purpose of this chamber is to accommodate a reflective shield or shutter 78 which is primarily usef-ul during the high temperature self-cleaning operation. During normal cooking operations, the shield 78 would be moved down into the bottom of the chamber 76 beneath the window openings, and hence would be out of sight. This movement is effected by a pair of handles 80 located on opposite sides of the shield 78 and which extend out through slots 81 provided for them in the embossment 32 of the inner door linear 26 is best seen in FIGURE 1. Thus, each slot 81 serves as a guide means for its respective handle 8%. Attention is called to the fact that these two handles 80 are inaccessible when the oven door 15 is closed (see FIGURES 1 and 4 in particular). Hence, it is only when the door is in an open position that the handles can be reached for manipulation.

The shield 78, in its raised position, is interposed between the glazing unit 56 and the innermost glass sheet 53. One important advantage of this is that the reflective shield prevents the escape of much of the radiant energy from within the oven cavity and this serves to increase the operating temperature of the glass sheet 53 and thereby automatically decomposes the food soil therefrom during the high temperature heat cleaning operation.

Preferably, guide means are provided for the proper movement of the reflective shield 78 within the door, as well as having snubbing means to retard any movement so that manual operation of the shield is required in order to change the position of the shield. As is shown in both FIGURES 2 and 3, a pair of clip members 85 are located in the chamber 76 beneath the window openings for bearing against both the side edge and rear side of the shield by means of runners 86 and spring fingers 87. As is best seen in FIGURE 4, each side edge of the shield 78 has a frontwardly-directed offset 90 which tends to straddle the glazing unit 56 and assist in the guiding action.

It is also well to provide a detent means for the shield 78 in its raised position to discourage the shield from falling inadvertently. This is best seen in FIGURE 2 in the form of a V-shaped cantilever spring 92 carried by the shield 78 and cooperating with a clip member 93 fastened to the inner side of the inner door liner 26 and having a rounded ledge 94.

As pointed out in the aforementioned Hurko patent, in a high temperature self-cleaning oven it is very important to provide a locking means for the oven door to insure that the high temperature cycle cannot be initiated unless the door is locked and also that the door cannot be unlocked unless the oven has cooled down to normal cooking temperatures. FIGURE 1 shows a handle 96 of a door latching mechanism in its open position. This latching mechanism is shown diagrammatically in FIGURE 5. This particular oven door latch mechanism is fully disclosed in the patent to Clarence Getman No. 3,189,375 which is assigned to the General Electric Company, assignee of the present invention. In addition to the handle 96, the latch mechanism includes a latching bolt 105 pivoted to a mounting bracket 106 by means of pin and slot connections 107 and 108. The latching bolt 105 is caused to swing in a horizontal plane when the handle 96 is actuated. When the handle 96 is unlocked the latching bolt 105 assumes a recessed or hidden position within the front edge of the cooktop 11 as is shown in FIGURES 1 and 2. When the handle 96 is locked, the latching bolt 105 swings out through a slot 110 in the cooktop and engages a keeper slot 98 formed in the oven door as seen in FIGURE 1. This particular latch mechanism is so constructed that it is prevented from moving to its locked position unless the door is in its closed position. The latch mechanism is provided with interlock switch means (not shown) interposed in the power circuit to the oven heating means and which closes the circuit to the heating means only when the oven door is closed and latched. See the co-pending application of Ronald B. Barber, Ser. No. 387,439, which is assigned to the General Electric Company, the assignee of the present invention.

The keeper slot 98 is adapted to be closed by a movable, L-shaped interlocking member 99 carried within the oven door and which is normally biased by spring means 100 to close the slot 98 as may be visualized from FIGURE 3. The actual keeper slot 98 is not shown in FIGURE 3 since it is formed in the inner door liner 26 which has been cut away to expose the interlocking member 99. Thus, if an attempt were made to close the handle 96 of the door latching mechanism to its locking position, the hook member or latching bolt 105 of the mechanism would strike the interlocking member 99 and be prevented from moving to a closed and locked position. This movable interlocking member 99 is adapted to be engaged and deflected by a projecting finger 101 of the reflective shield 78 when the shield is brought into its fully raised position. Hence, the keeper slot 98 is uncovered when, and only when, the reflector shield 78 is in its raised position to close the window. The advantage of having such an interlocking means 99 is to insure that the high temperature self-cleaning cycle cannot be initiated unless the window is first closed by raising the reflective shield 78. Accordingly, the housewife could not inadvertently initiate the self-cleaning cycle with the reflective shield 78 in its lowered or hidden position. In order to reinforce the interlocking member 6 99, a stationary guide plate, such as 103 and 104, is located on each side thereof so as to prevent the bending of the member 99 when the window is exposed and an attempt is made to lock the oven door.

Looking at FIGURE 1, a positive stop means such as a block 112 is positioned at each side of the oven door opening adjacent the top thereof so as to form a supporting ledge for the handle when the shield 78 is raised and the oven door closed as shown in FIGURE 3, thereby preventing the shield from dropping inadvertently.

As pointed out previously, it is contemplated that the oven heating elements 16 and 17, and the perimeter heater 37 will be controlled by the switch 20, thermostat 21 and timer 22 for effecting normal cooking and high temperature heat cleaning operations as described in the aforementioned Hurko Patent No. 3,121,158.

As described in that patent, for normal bake and broil operations, the oven selector switch 20 will be operated to the appropriate controlling position and the oven thermostat 21 operated to the selected cooking temperature. If desired, a timed-bake may be had by setting the oven selector switch 20 to a timed-bake position and setting the timer to the desired cooking time period, all as is conventional in electric ranges. For these operations, the window shield 78 will be in its lower window opening position so that the cooking operations may be viewed; also, the door latch 105 will be in its unlatching position as shown in FIGURES 1 and 5.

To effect the high temperature heat cleaning operation, the door shield 78, when the door is in its fully open position as shown in FIGURE 1 or in at least a partially open position, will be moved to close the windows by pulling the handles 80 outwardly to the position shown in FIGURE 1. Subsequently, when the door is closed these handles will move into positions above their respective 'blocks 112 so that the shield 78 will be held in its upper position, and, when the door is subsequently latched closed, cannot be lowered since the handles 80 will be inaccessible (FIG- URE 4). Also, when the shield 78 is raised (or moved outwardly as in FIGURE 1), it will engage the interlocking member 99 and move it against the spring 100 to clear the slot 98 so that the door latch handle 96 may be operated to latch the door closed.

This latching operation is one of the operations required to elfect the heat clean cycle. It is described generally as one of the operations to eifect this cycle described in the above-mentioned Hurko Patent No. 3,121,158. Also, as described therein, when other operations are effected, such as properly setting the selector switch 20, the oven thermostat 21 to clean and the timer 22 to clean, the high temperature heat clean cycle will be effected and operated for the time period set by the timer. During this operation it will be impossible to open the door until the door latching means is released and also impossible to lower the panel 78 because the door in its locked position will render the panel handles 80 inaccessible (FIGURE 4). During the clean cycle the shield will obstruct the view to the operator of the oven and more importantly will prevent a temperature rise in the outer windows to any degree substantially higher than the temperatures of the oven walls, which, as pointed out in the Hurko patent, will be held to the relatively low temperatures encountered in the relatively low temperature normal cooking operations.

Having described above a preferred embodiment of the present invention with its inherent advantages of safety, reliability and good engineering design, it will readily be apparent to those skilled in this art that the invention is centered in the door assembly, and that other feeler means than the hook member of the door latching mechanism may be used to cooperate with the shutter interlocking member 99 without departing from the scope of the present invention. For example, the feeler means could be a switch button of a door switch (not shown) mounted on the door frame and connected in either the power circuit or control circuit for the high temperature operating cycle. Such a switch could be a normally closed, single pole, single throw switch such that if the shutter 78 were not in its upper window closing position, the shutter interlock device 99 would cover the access opening comparable to slot 98 such that when the oven door is closed, the switch button would be depressed by the interlock device and thereby open the circuit through the switch and prevent the initiation of the high temperature operation. Furthermore, if the shutter were raised, the interlock device would uncover the access opening and the switch button would be allowed to freely enter the access opening when the oven door is closed so as to permit the high temperature operation, on the assumption that all other operating criteria have been met.

Modifications of this invention will occur to those skilled in this art and therefore it is to be understood that this invention is not limited to the particular embodiments disclosed, but that it is intended to cover all modifications which are within the true spirit and scope of this invention as claimed.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A door construction for a high temperature oven having an oven cavity formed by a box-like oven liner and a front-opening access door; the invention comprising a door having an outer door panel with a first window opening, a double-pane window assembly covering said first window opening, an inner door liner attached to and spaced inwardly from said outer door panel, a second window opening formed in said inner door liner, a glass pane covering said second window opening, a movable shutter interposed between said double-pane window assembly and said glass pane, said shutter having at least one handle along one side thereof, and slot means formed in the inner door liner for receiving a portion of the handle therethrough, whereby the position of the shutter may be adjusted manually when the door is open between a lower window open position and an upper window close-d position, a door latch keeper carried by said door, a movable closure plate positioned on the door and biased to a position to disable said keeper, and said shutter movable to engage and operate said closure plate away from said position to enable said keeper to lock said door when said shutter is closed'over said window assembly and so that said door may not be latched until said shutter is in its closed position.

2. An oven door comprising an outer door panel having a first window opening, an inner door liner spaced from said outer door panel, said inner door liner having a second window opening generally in alignment with the first window opening, and an inner panel of reduced size compared to the outer door panel and inner liner supported from the inner door liner and adapted to form one wall of the oven cavity, said inner panel having a third window opening, at least three glass panes positioned in the door to seal the window openings therethrough, a slidable shutter located for movement to a position between two adjacent panes to'obstruct the view through the door and restrict the radiation of heat through the window opening, the inner door liner having a door latching means that is adapted to cooperate with a mating element of the oven body for locking the door in a closed position, a movable interlocking member positioned in the door adjacent the said door latching means and normally biased to a position to disable the door latching means, the interlocking member being engaged by and deflected away from said position by the movement of the said shutter into its closed position to enable the door to be latched only when the shutter is closed.

3. An oven door comprising an outer door panel having a first window opening, an inner door liner attached to and spaced from the outer door panel, said inner door liner having a second window opening, at least three glass panes positioned in the door to seal the window openings therethrough, a slidable shutter located for movement into a closed position between two adjacent panes to obstruct the View through said window openings and restrict the radiation of heat through the window opening, the inner door liner having a door latching means that is adapted to cooperate with a mating element on an oven body for locking the door in a closed position, a movable interlocking member positioned in the door adjacent the said door latching means and normally biased to a position to disable the door latching means, the shutter in its closed position serving to deflect the interlocking member away from said position, whereby the door may not be locked unless the shutter is first closed, the shutter including a handle means that is accessible on the innermost side of the door so that the handle can only be manipulated when the door is unlocked and at least partially open.

4. An oven door comprising an outer door panel having a first window opening, an inner door liner attached to the outer door panel, said inner door liner having a second window opening, and an inner panel of reduced size compared to the outer door panel and inner liner supported from the inner door liner and adapted to form one wall of an oven cavity, the inner panel having a third window opening in alignment with the other two window openings, at multi-ply glass sheet glazing unit supported in the window openings between the outer door panel and the inner door liner, said glazing unit comprising a continuous spacer frame sandwiched between a pair of glass sheets, and fastening means for holding the glazing unit assembly together, a third glass sheet mounted over the second and third window openings, and a shutter carried by the door and adapted to be moved into a closed position between the glazing unit and the third glass sheet, said shutter having at least one handle along one side thereof, and slot means formed on the inside of the door for receiving a portion of the handle therethrough whereby the position of the shutter may be adjusted manually when the door is opened, the door having a hinged supporting edge and an opposite free edge remote therefrom, a door latching means located adjacent the free edge of the door and adapted to cooperate with a mating element of the oven body for locking the door in a closed position, a movable interlocking member located in the door and normally biased to a position to disable the door latching means, the interlocking member being deflected away from said position by the movement of the shutter into its closed position to enable the door to be latched only when the shutter is closed, the door, when locked, concealing said handle so that the shutter cannot be adjusted as long as the door is closed.

5. An oven door of hollow sheet metal construction provided with a transparent window formed by a plurality of glass sheets mounted therein, a shutter carried by the door and adapted to be moved from an open or a hidden position to a closed or visible position between certain of the glass sheets, the door having a hinged supporting edge and a free edge that is remote therefrom, a door latching means located adjacent the free edge of the door and adapted to cooperate with a mating element of an oven body for locking the door in a closed position, a movable interlocking member located in the door and normally biased to a position to disable the door latching means, the interlocking member being deflected away from said position by the positioning of the shutter in its closed position to enable the door to be latched only when the shutter is closed, and stop means adapted to engage the shutter when the door is locked so as to prevent the movement of the shutter when the door is locked.

6. An oven door of hollow sheet metal construction provided with a transparent window formed by a plurality of glass sheets mounted therein, a reflective shield carried by the door and adapted to be moved between a hidden position and a visible position between certain of the glass sheets, the shield having handle portions formed on opposite sides thereof and accessible on the inner side of the door, snubbing means formed in the door for retarding the movement of the shield within the door, thermal insulating material positioned within the door, and insulation guard means in the door for confining the insulating material from obstructing the transparent window and the movement of the reflective shield, insulation guard means also providing an air channel behind the front surface of the door with an air inlet means adjacent the bottom edge of the door and an air outlet means adjacent the top portion of the door for a natural sweep of relatively cool air through the air channel for dissipating some of the heat therefrom.

7. An oven door of hollow sheet metal construction with a transparent window formed by a plurality of glass sheets mounted therein, a reflective shield carried within the door and adapted to be moved between a lowered hidden position and a raised visible position between certain of the glass sheets, said shield having handles formed on opposite sides thereof and accessible from the inner side of the door, snubbing means between the door and the shield for retarding movement of the shield within the door, detent means between the door and the shield for supporting the shield in its raised position, a door latching means located adjacent the top edge of the door and adapted to cooperate with a'mating element of the oven body for locking the door in a closed position, movable interlocking member located within the door and normally biased to a position to disable the said door latching means, the interlocking member being deflected away from said position by the positioning of the reflective shield into its raised position covering the transparent window so as to enable the door to be latched only when the shield is raised.

8. An oven door comprising an outer panel and an inner door liner spaced inwardly therefrom substantially aligned window openings in said panel and door liner and glass panes closing said window openings, at slidable shutter mounted on said door for movement into a closed position between said glass panes to obstruct the view through and restrict the radiation of heat through said window openings and also movable to an open position to permit a view through said window openings, door latching means mounted on said door movable to a door locking position and to a door unlocking position, and means operated by said shutter when moved to said closed position to enable said door latching means to move'tosaid door locking position and to prevent movement thereof for said door unlocking position to said locking position when the shutter is in its open position.

9. A door construction for a high temperature oven having an oven cavity formed by a box-like oven liner and a front-opening access door; the invention comprising a door having an outer door panel with a first window opening, a double-pane window assembly covering said first window opening, an inner door liner attached to and spaced inwardly from said outer door panel, a second window opening formed in said inner door liner, a glass pane covering said second window opening, a movable shutter interposed between said double-pane window assembly and said glass pane, said shutter having at least one handle along one side thereof, and slot means formed in the inner door liner for receiving a portion of the handle therethrough, whereby the position of the shutter may be adjusted manually when the door is opened between a lower window open position and an upper window closed position, a shutter interlock device mounted within the door to sense the presence of the shutter in its upper window closing position, an access opening in the inner side of the door adjacent the interlock device, and biasing means normally to move the interlock device to cover the access opening when the shutter is in its lower window open position, while the movement of the shutter to its upper window closing position causes the shutter to engage the interlock device and shift it to uncover the access opening, the said access opening also being adapted to be entered by a feeler means supported from a door frame to which the said door is mounted when the said shutter is in its upper window closing position whereby the feeler means is unable to enter the access opening if the shutter is in any position other than its upper window closing position.

References Cited by the Examiner UNITED STATES PATENTS 1,417,976 5/1922 Curry et al 126200 2,489,962 11/ 1949 Hardwick 126200 2,926,658 3/1960 Ligon 126200 References Cited by the Applicant UNITED STATES PATENTS 2,963,019 12/ 1960 Domsky. 3,121,158 2/1964 Hurko. 3,189,020 6/ 1965 Getman.

KENNETH W. SPRAGUE, Primary Examiner. 

1. A DOOR CONSTRUCTION FOR A HIGH TEMPERATURE OVEN HAVING AN OVEN CAVITY FORMED BY A BOX-LIKE OVEN LINER AND A FRONT-OPENING ACCESS DOOR; THE INVENTION COMPRISING A DOOR HAVING AN OUTER DOOR PANEL WITH A FIRST WINDOW OPENING, A DOUBLE-PANE WINDOW ASSEMBLY COVERING SAID FIRST WINDOW OPENING, AN INNER DOOR LINER ATTACHED TO AND SPACED INWARDLY FROM SAID OUTER DOOR PANEL, A SECOND WINDOW OPENING FORMED IN SAID INNER DOOR LINER, A GLASS PANE COVERING SAID SECOND WINDOW OPENING, A MOVABLE SHUTTER INTERPOSED BETWEEN SAID DOUBLE-PANE WIINDOW ASSEMBLY AND SAID GLASS PANE, SAID SHUTTER HAVING AT LEAST ONE HANDLE ALONG ONE SIDE THEREOF, AND SLOT MEANS FORMED IN THE INNER DOOR LINER FOR RECEIVING A PORTION OF THE HANDLE THERETHROUGH, WHEREBY THE POSITION OF THE SHUTTER MAY BE ADJUSTED MANUALLY WHEN THE DOOR IS OPEN BETWEEN A LOWER WINDOW OPEN POSITION AND AN UPPER WINDOW CLOSED POSITION, A DOOR LATCH KEEPER CARRIED BY SAID DOOR, A MOVABLE CLOSURE PLATE POSITIONED ON THE DOOR AND BIASED TO A POSITION TO DIISABLE SAID KEEPER, AND SAID SHUTTER MOVABLE TO ENGAGE AND OPERATE SAID CLOSURE PLATE AWAY FROM SAID POSITION TO ENABLE SAID KEEPER TO LOCK SAID DOOR WHEN SAID SHUTTER IS CLOSED OVER SAID WINDOW ASSEMBLY AND SO THAT SAID DOOR MAY NOT BE LATCHED UNTIL SAID SHUTTER IS IN ITS CLOSED POSITION. 